fix undefined variables, added jshint checks, closes #102

.jshintrc

@@ -25,5 +25,18 @@
     "sub"           : false,  // Tolerate all forms of subscript notation besides dot notation e.g. `dict['key']` instead of `dict.key`.
     "trailing"      : false,   // Prohibit trailing whitespaces.
     "white"         : false,  // Check against strict whitespace and indentation rules.
-    "indent"        : 4       // Specify indentation spacing
+    "indent"        : 4,       // Specify indentation spacing
+
+    // variables
+    "undef": true,
+    "-W079": true,            // Silence redefinition errors (they are false positives).
+    "predef": [
+        "Matter", "window", "document", "Element", "MatterTools", "PIXI", 
+        "$", "Image", "navigator", "setTimeout", "decomp", "HTMLElement",
+        "Body", "Composite", "World", "Contact", "Detector", "Grid", 
+        "Pairs", "Pair", "Resolver", "SAT", "Constraint", "MouseConstraint", 
+        "Common", "Engine", "Mouse", "Sleeping", "Bodies", "Composites", 
+        "Axes", "Bounds", "Vector", "Vertices", "Render", "RenderPixi", 
+        "Events", "Query", "Runner", "Svg", "Metrics"
+    ]
 }

src/collision/Resolver.js

@@ -51,6 +51,7 @@ var Resolver = {};
             normal,
             bodyBtoA,
             contactShare,
+            positionImpulse,
             contactCount = {},
             tempA = Vector._temp[0],
             tempB = Vector._temp[1],

src/geometry/Svg.js

@@ -26,7 +26,7 @@ var Svg = {};
         var i, il, total, point, segment, segments, 
             segmentsQueue, lastSegment, 
             lastPoint, segmentIndex, points = [],
-            length = 0, x = 0, y = 0;
+            lx, ly, length = 0, x = 0, y = 0;
 
         sampleLength = sampleLength || 15;
 

src/render/Render.js

@@ -387,7 +387,8 @@ var Render = {};
             options = render.options,
             body,
             part,
-            i;
+            i,
+            k;
 
         for (i = 0; i < bodies.length; i++) {
             body = bodies[i];
@@ -684,7 +685,8 @@ var Render = {};
             options = render.options,
             body,
             part,
-            i;
+            i,
+            k;
 
         c.beginPath();